{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-41591", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-04-21T14:15:21.960Z", "datePublished": "2026-05-08T15:22:50.990Z", "dateUpdated": "2026-05-08T21:26:58.356Z"}, "containers": {"cna": {"title": "Marko: XSS via case-insensitive script/style closing tag bypass in runtime HTML escaping", "problemTypes": [{"descriptions": [{"cweId": "CWE-79", "lang": "en", "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.4, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq"}], "affected": [{"vendor": "marko-js", "product": "marko", "versions": [{"version": "marko < 5.38.36", "status": "affected"}, {"version": "@marko/runtime-tags < 6.0.164", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-05-08T15:22:50.990Z"}, "descriptions": [{"lang": "en", "value": "Marko is a declarative, HTML-based language for building web apps. Prior to marko version 5.38.36 and prior to @marko/runtime-tags 6.0.164, when dynamic text is interpolated into a <script> or <style> tag the Marko runtime failed to prevent tag breakout when the closing tag used non-lowercase casing. An attacker able to place input inside a <script> or <style> block could break out of the tag with </SCRIPT>, </Style>, etc. and inject arbitrary HTML/JavaScript, resulting in cross-site scripting. This issue has been patched in marko version 5.38.36 and @marko/runtime-tags 6.0.164."}], "source": {"advisory": "GHSA-x9fj-57fh-c8wq", "discovery": "UNKNOWN"}}, "adp": [{"references": [{"url": "https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-05-08T17:08:43.350843Z", "id": "CVE-2026-41591", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-05-08T21:26:58.356Z"}}]}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "Marko is a declarative, HTML-based language for building web apps. Prior to marko version 5.38.36 and prior to @marko/runtime-tags 6.0.164, when dynamic text is interpolated into a <script> or <style> tag the Marko runtime failed to prevent tag breakout when the closing tag used non-lowercase casing. An attacker able to place input inside a <script> or <style> block could break out of the tag with </SCRIPT>, </Style>, etc. and inject arbitrary HTML/JavaScript, resulting in cross-site scripting. This issue has been patched in marko version 5.38.36 and @marko/runtime-tags 6.0.164."}], "id": "CVE-2026-41591", "lastModified": "2026-05-13T16:34:56.063", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.4, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 3.1, "impactScore": 2.7, "source": "security-advisories@github.com", "type": "Secondary"}]}, "published": "2026-05-08T16:16:11.167", "references": [{"source": "security-advisories@github.com", "url": "https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://github.com/marko-js/marko/security/advisories/GHSA-x9fj-57fh-c8wq"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-79"}], "source": "security-advisories@github.com", "type": "Secondary"}]}

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